Michael Ort: Volcanology, igneous petrology, and
geochemistry

Research activities

My research into eruption and emplacement
processes of pyroclastic flows and surges has focused on large-volume
ignimbrites in Argentina and Italy and on maar volcanoes in Arizona, Alaska,
and Italy.

The driving question is how do these
pyroclastic gravity currents form and move. Because we really only have
deposits to work with, my research designs aim to cut through the
"filter" of the deposition to get at what the current looked and
acted like , at least in the lower part, near the depositional zone. I commonly
use careful field work, petrography (optical and electron), and paleomagnetism (especially
anisotropy of magnetic susceptibility) as tools. My petrologic interests
currently center on the origins of the Hopi Buttes (NE Arizona) monchiquitic
and nephelinitic magmas. I have an isotope clean lab and am a co-PI on our new
multi-collector ICP mass spectrometer, on which we can do much of the analysis.

I am also currently working on the
interaction between humans and the youngest volcanism in the Southwestern USA,
concentrating on the ~1050 AD Sunset Crater eruption near Flagstaff and the
Little Springs eruption (dated between 1100 and 1200 AD). Both eruptions had
profound effects on the people living there then, so I am working with an
archaeologist and other geologists to understand how the environment changed.

My previous research has included the
effects of acid rain, volcanic emissions, and sulfide mineral deposits on
terrestrial and aquatic ecosystems in North America, South America, and
Scandinavia, and on the biogeochemistry of Southwestern US rivers.

I now work with the Grand Canyon
Monitoring and Research Center of the U.S. Geological Survey performing
biogeochemical and geomorphological research and monitoring to aid in adaptive
management of the Glen Canyon Dam and the Colorado River’s flow through Grand
Canyon. I have a long-term interest in
the impacts of acid deposition, acid mine drainage, and acid rock drainage on
the alpine and subalpine ecosystems of the Rocky Mountain west, particularly
Southwestern Colorado. I’m also interested in the controls on and dynamics of
travertine deposition in rivers of the Southwest.

Jim Sample: Low-temperature geochemistry

Research activities

My research focuses on fluid flow in the upper
crust in active tectonic environments.

I am interested in developing new ways
to investigate the record of fluid flow in fault systems in order to understand
the plumbing of fluid systems and how fluid-rock interactions affect rock
properties over short and long time periods.

The results of this research bears on the
evolution of fluid circulation in the crust, deformation mechanisms and
seismicity at active margins, redistribution of elements in the marine system,
and perhaps on the evolution of life in extreme environments. My students,
colleagues, and I investigate these processes using a variety of analytical
techniques. Each project involves a substantial component of:

field mapping

rock characterization

sample collection—using the good old
Brunton compass

high-precision mapping

tools for field measurement of rock
permeability.

We characterize the cements and fabrics
of the samples using petrography and image analysis including scanning electron
microscopy and associated imaging techniques. We try to unravel fluid flow
histories and the evolution of fluid sources by combining petrographic studies
with mass spectrometry, focusing on the trace-element, stable, and radiogenic
isotope geochemistry of precipitates left behind by fluids passing through the
system.

My current areas of research are
carbonate cements and veins preserved in active faults in the Cascadia
subduction zone, deformation bands and petroleum migration along the Newport-
Inglewood fault zone in southern California, a Paleocene cold seep deposit
(chemoherm) on the west side of the San Joaquin Valley, California, and fault
systems in coarse-grained clastic rocks of the Colorado Plateau. In addition to
basic scientific research, I am involved in projects to improve and increase
Earth science education at the K-16 level.